1 Answer

You program connected device to publish a set of its property values or ‘state (“I am ON and my color is RED”) to the AWS IoT Core service.

The last reported state is stored in the Device Shadow in AWS IoT Core.

An application (such as a mobile app controlling the light bulb) uses a RESTful API to query AWS IoT Core for the last reported state of the light bulb, without the complexity of communicating directly with the light bulb.

When a user wants to change the state (such as turning the light bulb from ON to OFF), the application uses a RESTful API to request an update, i.e. sets a ‘desired’ state for the device in AWS IoT Core. AWS IoT Core takes care of synchronizing the desired state to the device.

The application gets notified when the connected device updates its state to the desired state.